The ability to reduce the size of an object is typically an important advance in different fields of technology, where such reduction increases efficiency, reduces cost and promotes portability, as evident by the success of traditional semiconductor techniques. In response, different industries have incorporated and modified various semiconductor techniques to reduce the size and cost of different products, e.g., various fluid delivery systems.
One example is the field of microfludic devices and methods as disclosed in U.S. Pat. No. 5,585,069 (Partitioned Microelectronic And Fluidic Device Array For Clinincal Diagnostics And Chemical Synthesis) and U.S. Pat. No. 5,603,351 (Method And System For Inhibiting Cross-Contamination In Fluids Of Combinatorial Chemistry Device), which are incorporated herein by reference. These devices provide arrays having micron sized reservoirs and channels for delivery of a very small amount of fluids to a specific location, e.g., a receptor or reaction cell on the array.
Another example is the field of inkjet printing which offers a variety of techniques to print information, e.g., text and images, onto a receptor, such as paper, Mylar sheet or coated material. Many of the printing techniques are based on the physical transport of a pigment or ink from a reservoir to a receptor in a controlled manner. For example, FIG. 1 illustrates a typical printing system 100, which can be represented by three broad parts: 1) a storage 110 for the pigment, 2) a transport mechanism 120 to deliver the pigment and 3) a receptor 130 to receive the pigment, e.g., a print media.
The storage 110 can be implemented in a number of different manners, e.g., a toner cartridge for a laserjet printer that carries pigment in powder form, an inkjet cartridge for an inkjet printer that carries liquid pigment or a print ribbon in a dot matrix printer.
Similarly, the transport mechanism 120 can be implemented in a number of different manners, e.g., the formation and propulsion of droplets (or a spray of droplets) by mechanical means like thermal evaporation, acoustic waves or electrical means. Typically, the droplets exit the storage medium and travel a gap to reach the receptor. An example of droplets (or sprays) propulsion is illustrated by Choi et al., in Society for Imaging Science and Technology, pages 33-35, (1996), which incorporates electro-hydrodynamic (EHD) techniques for printing. An example of droplet formation is also illustrated by Crowley, U.S. Pat. No. 4,220,958 (Ink Jet Electrohydrodynamic Exciter).
However, the careful delivery of a large quantity of small amounts of fluid requires a complex control apparatus and method. Using the field of printing as an example, printing an image onto a receptor can, in principle, be accomplished one dot at a time. However, even small, low-resolution images may have many dots, and the process of printing a dot and moving the print head (or receptor) to the next dot location is relatively slow. Therefore, a print head may consist of multiple printing elements that print in parallel onto a first printing area and then the print head is moved to the next printing area and so on.
The number of positions that the print head must occupy relative to the receptor in order to print an entire image is simply the total number of possible dot locations divided by the number of printing elements in the print head. In order to minimize printing time, it is advantageous to maximize the number of printing elements on the print head.
However, some geometrical arrangements of printing elements are easier to drive or address than others. For example, a linear array of elements is simple to address, even when the total number of elements is large. All that is required is a linear array of multi-output drivers attached along the length of the array, where one driver output directly addresses one printing element. However, for a large array, many drivers are needed. For example, a 1000-element linear array requires 1000 drivers. For such a large array, arranging the printing elements in a two-dimensional matrix pattern is preferable. However, although a matrix pattern reduces electrical connections in general, such reduction is achieved at the expense of increasing the complexity in addressing such a large array of printing elements.
Therefore, a need exists in the art for an apparatus and concomitant method for controlling a plurality of fluid delivery elements to deliver fluids to a receptor.